In cellular network systems, multiple-input and multiple-output, or MIMO may be used for improving the communication performance by using multiple antennas at both the transmitter and receiver. MIMO rank adaptation may be employed at the transmitter side as part of the link adaptation process to make best use of the multiple transmit antennas. If the user equipment (UE) channel quality is good, multiple data streams could be sent to the UE using high rank transmission. If the channel is poor, a low transmission rank may exploit the MIMO diversity gain to improve the received signal to interference plus noise ratio (SINR). At the receiver side, the SINR can be improved by combining the signals from multiple receiving antennas. An IRC (interference rejection combining) receiver may exploit the interference correlation across the receiving antennas to suppress the strongest interferers and maximize the SINR. It may experience each MIMO rank as one independent interference source. Therefore, its performance may be significantly penalized when high rank transmissions are applied at interfering base stations or eNBs.
An IRC receiver with Nrx antennas can ideally suppress up to Nrx−1 strongest interferers. If rank 1 transmission is used in all neighboring cells, the interference from Nrx−1 neighboring cells can be suppressed. It should be noted that more than one cell can be provided by a single base station. However, if neighboring cells are using high rank transmission, one interferer corresponds to one MIMO data-stream, and the IRC receiver can suppress interference from only (Nrx−1)/Nrank neighboring cells. Therefore, the benefit of using IRC may be reduced. This effect may be significant for cell-edge UEs who suffer from severe inter-cell interference.
There may be a need for an improved system and method being adapted to reduce the interferences between neighboring cells and to increase the benefit of using an IRC receiver.